JP4904505B2 - Phytoplankton distribution measuring method and apparatus - Google Patents

Description

  The present invention relates to a phytoplankton distribution measuring method and apparatus for measuring a phytoplankton distribution by allowing a measuring device to freely fall in water.

  With the warming of seawater, phytoplankton such as dinoflagellates, flagellates, cilia, and diatoms proliferate in large quantities, and red tides that cause great damage to seafood and seaweed frequently occur. In recent years, the cultivation of seafood has become popular, so it is necessary to know the occurrence of red tide at an early stage and move the seafood.

  For this reason, various types of submerged plankton detectors have been proposed which are thrown into the water and allowed to fall freely and measure the actual phytoplankton distribution in the water.

  Conventionally, a light emitting diode and a light receiving unit are provided on the side surface of the measuring instrument, and light having a wavelength that excites the pigment of the underwater plankton is emitted from the light emitting diode, and the light emitted from the underwater plankton is received by the light receiving unit. An underwater plankton sensor that quantifies the amount of underwater plankton based on the amount of received light is known (see Japanese Patent Application Laid-Open No. 8-15157).

  However, the above-mentioned conventional plankton sensor is formed in a cylindrical shape with the tip surface depressed, so that turbulent flow is generated in the surroundings when falling in the water, and therefore, the phytoplankton is disturbed and an accurate distribution situation is obtained. Cannot measure.

  In addition, since the light emitting diode that irradiates the diffused light and the light receiving portion that spreads as the light receiving region moves away from each other are arranged close to each other in the sensor unit, it is difficult to accurately define the measurement region. Both the fluorescence emitted by the distributed phytoplankton and the fluorescence emitted by the phytoplankton distributed far from the sensor unit are detected, and the measurement result tends to be inaccurate.

  Therefore, in order to limit the measurement area, a light receiving window is provided on the side surface of the detector body, a plurality of light transmitting windows are provided in an annular shape surrounding the light receiving window, and a light emitting diode is provided behind the light transmitting window. A fluorescence detector has been proposed in which the irradiation direction intersects with the center line of the light receiving hole (see Japanese Patent Application Laid-Open No. 8-261934).

  However, since this fluorescent detector also uses a normal light emitting diode as the light emitting part, the irradiated light diffuses and the area that overlaps the light receiving area of the light receiving part (that is, the measurement area) is widened. The distribution density of phytoplankton in Japan cannot be measured accurately, and the measurement accuracy is inevitably coarse.

  In addition, since this fluorescence detector is mounted on a cylindrical probe, it is not possible to prevent disturbance of the water flow around the injection point.

An object of the present invention is hardly disturbed water flow device is turned point, it is possible to define narrow the measurement range, which can be fine measurement in natural state near, to provide a distribution meter HakaSo location phytoplankton is there.

Distribution measuring method of the phytoplankton of the invention, at lower end streamlined, the probe light receiving portion disposed below the laser emission unit and the laser light emitting portion is mounted therein, to fall freely water upright during dropping, the pulsed laser beam having a wavelength that excites the by land chlorophyll dye to said laser light emitting portion, into the water from the side of the probe, is irradiated obliquely downward at an angle that intersects the light receiving region of the light receiving portion, Upon receiving the pulsed laser light, the light emitted from the phytoplankton in the intersecting region where the light receiving region of the light receiving unit and the irradiation region of the laser light emitting unit intersect is detected by the light receiving unit , and the amount of received light detected by the light receiving unit by the amount of phytoplankton measured depth direction to adjust the angle of inclination with respect to the probe of the laser light emitting portion, from the probe of the intersection region Distance to adjust.

The phytoplankton distribution measuring apparatus according to the present invention falls in an upright state in water, has a streamlined probe at the lower end , and is disposed in the probe , and has a wavelength that excites chlorophyll dye from the side of the probe into the water. A laser light emitting unit that irradiates pulse laser light obliquely downward at a predetermined period; and a light receiving unit that is disposed below the laser light emitting unit in the probe and detects fluorescence incident from a side surface of the probe, and The light receiving region of the light receiving unit intersects the laser light irradiation direction of the laser light emitting unit, receives the pulse laser light emitted from the laser light emitting unit , and receives the light receiving region of the light receiving unit and the irradiation region of the laser light emitting unit. DOO has received the phytoplankton emits fluorescence intersecting region that intersects with the light receiving unit, the water the amount of phytoplankton by the received light amount Measured in the direction, as adjustable inclination angle with respect to the probe of the laser light emitting portion is of the intersection region, the distance from the probe be adjustable.

  According to the present invention, since the lower end portion of the probe is streamlined, the water flow at the measurement site is not easily disturbed, so that the distribution of phytoplankton can be measured in a state close to nature, and the measurement accuracy is increased.

  In addition, highly focused pulsed laser light is emitted from the light emitting part so as to intersect the light receiving area of the light receiving part, so that the measurement area can be very limited and narrowed. As a result, the distribution of phytoplankton at each water depth Can be measured precisely and accurately.

It is sectional drawing of the underwater measuring apparatus incorporating one Example of the phytoplankton distribution measuring apparatus by this invention. It is sectional drawing of the distribution measuring apparatus of the phytoplankton attached to the lower end of the underwater measuring apparatus of FIG. It is principal part sectional drawing of the distribution measuring apparatus of the phytoplankton of FIG. It is sectional drawing of the underwater measuring device for experiment which attached the distribution measuring device of the phytoplankton of FIG. It is a figure which shows the time-dependent change of the deviation of the water temperature which the water temperature sensor of the experimental underwater measuring apparatus of FIG. 4 detected, and the temperature of the water with which the water tank was filled. It is a figure which shows the time-dependent change of the fluorescence intensity which the light-receiving part detected in the distribution measurement apparatus of the phytoplankton attached to the underwater measurement apparatus for experiment of FIG. It is a figure which shows the power spectrum of the measured temperature (FIG. 5) and fluorescence intensity (FIG. 6).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the phytoplankton distribution measuring device 1 of the present invention is installed along the axial direction at the lower end of an underwater measuring device 2 which is thrown into water and freely falls. A floating body 3 is attached to the upper part of the underwater measuring device 2 in order to balance when descending underwater and adjust the descending speed.

  In addition to the distribution measurement device 1, other sensors 4 such as a depth sensor and a thermometer, and a protective rod 5 longer than the distribution measurement device 1 and other sensors 4 are attached to the lower end of the underwater measurement device 2. . The protective bar 5 is for preventing the distribution measuring device 1 and other sensors 4 from colliding with an object and being damaged during dropping. The other sensors 4 and protective rods 5 are all streamlined at their tips so as not to disturb the surrounding water flow.

  As shown in FIG. 2, the phytoplankton distribution measuring device 1 includes a pipe-like support portion 6 attached to the lower end of the underwater measurement device 2 and a laser fluorescent probe 7 attached to the lower end of the support portion 6. In the interior of the laser fluorescent probe 7, a laser light emitting unit 8, a light receiving unit 9, and a control circuit (not shown) are accommodated.

  The laser fluorescent probe 7 is formed of a streamlined cylinder at the lower end, and a light emitting window 10 and a light receiving window 11 are formed side by side on the side thereof. A laser light emitting unit 8 is installed inside the light emitting window 10, and a light receiving unit 9 is installed inside the light receiving window 11.

  As shown in FIG. 3, the laser light emitting unit 8 includes a heat radiating housing 12, a laser light emitting element 13, and a condenser lens 14.

  A condensing lens 14 is installed in the light emitting window 10 of the laser fluorescent probe 7, a heat radiating housing 12 is disposed in the back thereof, and a laser light emitting element 13 is accommodated in the heat radiating housing 12 with the irradiation part facing the condensing lens 14. ing.

The laser light oscillated by the laser light emitting element 13 is focused to a diameter of about 2 mm by the condenser lens 14, and a pulse laser light having a peak at a wavelength of 407 nm for exciting the chlorophyll pigment of phytoplankton is emitted from the laser light emitting unit 8. Irradiation is performed at 2.778 × 10 ⁻⁴ seconds and a pulse period of 5.556 × 10 ⁻⁴ seconds.

  The light receiving unit 9 includes a filter 15 and a light receiving element 16. The filter 15 selectively transmits light having a wavelength of 610 nm or more and is placed on the inner surface of the transparent pressure-resistant plastic plate 18 fitted in the light receiving window 11. The light receiving element 16 faces the light receiving surface toward the light receiving window 11 behind the filter 15. Installed.

  Further, the light receiving region of the light receiving unit 9 spreads away from the light receiving window 11 with the axis a orthogonal to the central axis of the underwater measuring device 2 as the center, and the top angle of the light receiving region is 20 degrees.

  Then, the pulsed laser beam p having a predetermined width irradiated from the laser light emitting unit 8 intersects the light receiving region of the light receiving unit 9, so that the intersected region (indicated by the oblique lines in FIG. 3) is the measurement region b. Become.

  The laser emission unit 8 is attached to the probe 7 so that the tilt angle can be adjusted with respect to the central axis of the probe 7 (parallel to the central axis of the underwater measuring device 2). Therefore, the intersection angle between the central axis a of the light receiving region of the light receiving unit 9 and the pulsed laser light p emitted from the laser light emitting unit 8 can be changed. As shown in FIG. 3, when the irradiation direction of the pulse laser beam p is adjusted downward by approximately 45 ° with respect to the central axis of the probe 7, the measurement region b (the light receiving region of the light receiving unit 9) is positioned relatively close to the probe 7. And a region where the irradiation region of the laser light emitting unit 8 intersects), and when the distribution measuring device 1 is lifted from the water, the pulse laser beam p irradiates the human eyes and prevents an accident. Can do. The distance of the measurement region b from the probe 7 can be changed by adjusting the mounting angle of the laser emitting unit 8.

  The distribution of phytoplankton is measured as follows.

  When the cable 17 is attached to the upper end of the floating body 3 and the underwater measuring device 2 is thrown into the water, the underwater measuring device 2 naturally falls in water in an upright state with the phytoplankton distribution measuring device 1 and other sensors 4 facing down. To do.

  The pulsed laser light p transmitted from the laser emission unit 8 during the fall is irradiated obliquely downward into the water from the side surface of the laser fluorescent probe 7.

  Since the chlorophyll pigment of phytoplankton emits fluorescence by excitation light having a wavelength of about 430 nm, the phytoplankton in the irradiation range of the laser emission unit 8 receives the irradiated pulse laser beam p and has the same period as the pulse laser beam p. Flickers fluorescence.

  The fluorescence emitted by the phytoplankton distributed in the measurement region b upon receiving the pulsed laser light p reaches the light receiving window 11 formed on the side surface of the laser fluorescent probe 7. Since the wavelength of fluorescence passing through the light receiving window 11 is 677 nm, the light passes through the filter 15 installed on the inner surface of the light receiving window 11 and is detected by the light receiving element 16. Light whose wavelength does not reach 600 nm is blocked by the filter 15 and is not detected by the light receiving element 16.

  The fluorescence detected by the light receiving element 16 is detected by the control circuit, and only the light that blinks in the same cycle as the pulsed laser light p emitted from the laser light emitting unit 8 is identified as the fluorescence to be measured. It is extracted as a signal and quantified by a signal processing computer.

  Since the intensity of the pulsed laser beam p emitted from the laser emission unit 8 is constant, the amount of phytoplankton distributed in the measurement range b is proportional to the amount of fluorescence emitted by the phytoplankton. Therefore, the amount of phytoplankton can be measured by the amount of light received by the light receiving unit 9.

  In order to test the resolution of the phytoplankton distribution measuring apparatus 1, the following experiment was performed.

  As shown in FIG. 4, a high-sensitivity water temperature sensor 19 was attached adjacent to the phytoplankton distribution measuring device 1 to obtain an experimental underwater measuring device 20.

  The sensor part of the high-sensitivity water temperature sensor 19 is arranged very close to the estimated measurement position (intersection of the pulse laser irradiation direction of the laser light emitting part 8 and the central axis a of the light receiving part 9). The horizontal distance from the side surface is 10 mm and is located 5 mm above the center axis of the light receiving element 16.

  The green juice filtered through a 52 micron filter (Daisha Co., Ltd., with barley wakana) was dissolved in 7 liters of water at 10 ° C. to prepare a 1 ppb green juice solution.

  A water tank of 0.7 m (W) × 0.75 m (H) × 13 m (L) was filled with water having a water temperature of 12.7 ° C., and the green juice solution was put into this water tank.

  On the upper surface of the water tank, a guide rail is installed along its longitudinal direction, and the experimental underwater measuring device 20 is slidably attached to the guide rail so as to be immersed in water.

Then, a pulse laser beam p having a wavelength of 407 nm was irradiated from the laser light emitting unit 8 with a pulse width of 2.778 × 10 ⁻⁴ seconds, a pulse period of 5.556 × 10 ⁻⁴ seconds, and a luminous flux of 2 mm. As the light receiving element 16, an element that selectively receives light having a wavelength of 677 nm was installed.

  While moving the experimental underwater measuring device 20 along the guide rail at a speed of 10 cm / sec with the lower end in front, the water temperature detected by the high sensitivity water temperature sensor 19 and the temperature of the water filled in the water tank (12. 7 ° C.) and the fluorescence intensity detected by the light receiving unit 9 was measured. The results are shown in FIGS. 5 and 6, respectively, and the power spectra of both are shown in FIG.

  The water temperature of the solution and the distribution of the fluorescent substance in the water tank due to the green juice are almost the same immediately after the solution is charged.

  As is clear from FIGS. 5 and 6, the fluorescence intensity received by the light receiving element 16 and the water temperature measured by the high sensitivity water temperature sensor 19 have a high correlation.

  Therefore, the light receiving element 16 measures the fluorescence intensity in a very narrow range at a position very close to the sensor portion of the high-sensitivity water temperature sensor 19, that is, a position very close to the phytoplankton distribution measuring device 1 itself. I understand that.

  From the power spectrum shown in FIG. 7, it can be seen that the resolution of the phytoplankton distribution measuring apparatus 1 is higher than that of the high-sensitivity water temperature sensor 19.

Claims (2)

Step lower end streamlined, the probe light receiving portion disposed below the laser emission unit and the laser light emitting portion is mounted therein, to free fall in water in an upright state,
A step of irradiating a pulsed laser beam having a wavelength for exciting a chlorophyll dye by the laser emitting unit into the water from the side of the probe obliquely downward at an angle crossing the light receiving region of the light receiving unit during the fall of the probe,
Step wherein upon receiving a pulsed laser beam to detect the phytoplankton emits fluorescence intersection region where the irradiation area of the light receiving area and the laser emission portion of the light receiving portion intersect at the light receiving unit,
In the method for measuring the distribution of phytoplankton, including the step of measuring the amount of phytoplankton in the direction of water depth according to the amount of light detected by the light receiving unit ,
The phytoplankton distribution measuring method , wherein the distance of the intersecting region from the probe is adjusted by adjusting an inclination angle of the laser emitting unit with respect to the probe . A probe whose bottom end is streamlined and falls while standing upright in water,
A laser emitting unit that is disposed in the probe and irradiates a pulse laser beam having a wavelength that excites a chlorophyll dye obliquely downward into the water from the side surface of the probe;
A light receiving portion that is disposed below the laser light emitting portion in the probe and detects fluorescence entering from the side surface of the probe;
The laser light emitting direction of the laser light emitting unit intersects the light receiving region of the light receiving unit, receives pulsed laser light emitted from the laser light emitting unit, and irradiates the light receiving region of the light receiving unit and the laser light emitting unit. Fluorescence emitted from the phytoplankton in the intersecting region where the region intersects is received by the light receiving unit, the amount of phytoplankton is measured in the depth direction according to the amount of received light, and the tilt angle of the laser emitting unit with respect to the probe can be adjusted, The distance of the intersecting region from the probe is adjustable.
Phytoplankton distribution measuring device.

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